handkerchief code
noun1
The display of handkerchiefs of various colors used as a coded way to indicate the sexual interests of the wearer.
- Because S&M is in the news this year: the Village Voice, Boston Globe, Time. They tell of all those big, mean men in leather and denim, keys dangling from leather straps, spiked dog collars around the necks. Between the key code (keys on the left—S; keys right—M) and the handkerchief code (color worn denotes favorite sexual act), the men don't even have to talk to each other.1976 February 7, Rosenjoy, “Sadomasochism: The Theory And The Practice”, in Gay Community News, volume 3, number 32, page 10: